Link adaptation enhancements

ABSTRACT

Certain aspects relate to methods, apparatuses, computer readable mediums and wireless nodes. For example, an apparatus generally includes an interface configured to obtain, during a TXOP owned by a second apparatus, at least one first frame from the second apparatus and a processing system configured to (i) determine a MCS associated with the at least one first frame, (ii) increase a value of a counter if the MCS associated with the at least one first frame is the same as a MCS associated with a frame previously obtained by the apparatus during the TXOP and (iii) take one or more actions based on the counter value.

BACKGROUND

Field

The present disclosure generally relates to communications networks, andmore particularly, to methods and apparatuses directed to linkadaptation.

Background

Wireless communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources.

These wireless communication networks may be multiple-access networkscapable of supporting multiple users by sharing the available networkresources. Examples of such multiple-access networks include CodeDivision Multiple Access (CDMA) networks, Time Division Multiple Access(TDMA) networks, Frequency Division Multiple Access (FDMA) networks,Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networksand Wi-Fi networks.

Within such wireless communication networks, a variety of data servicesmay be provided, including voice, video, and emails. More recently,wireless communication networks are being used for an even broader rangeof services and larger numbers of users. As the demand for mobilebroadband access continues to increase, research and developmentcontinue to advance wireless communication technologies not only to meetthe growing demand for mobile broadband access, but to advance andenhance the user experience.

BRIEF SUMMARY

The systems, networks, methods, devices and apparatuses of thedisclosure each have several aspects. No single one of the aspects issolely responsible for desirable attributes of such systems, networks,methods, devices and apparatuses. Without limiting the scope of thisdisclosure as expressed by the claims which follow, some aspects willnow be discussed briefly. After considering this discussion, andparticularly after reading the section entitled “Detailed Description”one will understand how the aspects of this disclosure provideadvantages that include improved communications between wireless nodesin a wireless network.

Certain aspects provide an apparatus for wireless communication. Theapparatus generally includes (a) a processing system configured to (i)obtain a transmission opportunity (TXOP), (ii) generate a plurality offirst frames, wherein one or more of the first frames include a controlfield having a first value and one or more of the first frames includedata and (iii) apply a first modulation and coding scheme (MCS) to theplurality of the first frames and (b) an interface configured to (i)output the modulated and coded first frames for transmission to a secondapparatus during the TXOP, wherein the first value indicates the secondapparatus can only transmit control information during the TXOP and (ii)obtain, during the TXOP, an acknowledgment (ACK) frame indicating dataof at least one of the first frames was received by the secondapparatus. Furthermore, the processing system is further configured todetermine a first error rate based on the ACK frame and compare theerror rate to a target error rate and take one or more actions based onthe comparison.

Certain aspects provide an apparatus for wireless communication. Theapparatus generally includes an interface configured to obtain, during aTXOP owned by a second apparatus, at least one first frame from thesecond apparatus and a processing system configured to (i) determine aMCS associated with the at least one first frame, (ii) increase a valueof a counter if the MCS associated with the at least one first frame isthe same as a MCS associated with a frame previously obtained by theapparatus during the TXOP and (iii) take one or more actions based onthe counter value.

Aspects generally include methods, apparatuses, computer readablemediums and wireless nodes, as substantially described herein withreference to and as illustrated by the accompanying drawings. Numerousother aspects are provided.

To the accomplishment of the foregoing and related ends, the one or moreaspects include the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a diagram of an example wireless communications network, inaccordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram of an example access point and examplestations, in accordance with certain aspects of the present disclosure.

FIG. 3 illustrates an example wireless device, in accordance withcertain aspects of the present disclosure.

FIG. 4 illustrates messages being exchanged between an initiator and aresponder during a transmission opportunity owned by the initiator andwith a reverse direction bit initially set to 0 in accordance withcertain aspects of the present disclosure.

FIG. 5 is a flow diagram of example operations for wirelesscommunications, in accordance with certain aspects of the presentdisclosure.

FIG. 5A illustrates example components capable of performing theoperations shown in FIG. 5, in accordance with certain aspects of thepresent disclosure.

FIG. 6 illustrates messages being exchanged between an initiator and aresponder during a transmission opportunity owned by the initiator andwith the reverse direction bit initially set to 1 in accordance withcertain aspects of the present disclosure.

FIG. 7 is a flow diagram of example operations for wirelesscommunications, in accordance with certain aspects of the presentdisclosure.

FIG. 7A illustrates example components capable of performing theoperations shown in FIG. 7, in accordance with certain aspects of thepresent disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially used on other aspects without specific recitation.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects.

The word “communicate” is used herein to mean “transmit”, “receive” or“transmit and receive”. The word “communications” is used herein to mean“transmission”, “reception” or “transmission and reception”.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

The following description is directed to certain implementations for thepurposes of describing the innovative aspects of this disclosure.However, a person having ordinary skill in the art will readilyrecognize that the teachings herein can be applied in different ways andmay be incorporated into various types of communication networks ornetwork components. In some aspects, the teachings herein may beemployed in a multiple-access network capable of supportingcommunication with multiple users by sharing the available networkresources (e.g., by specifying one or more of bandwidth, transmit power,coding, interleaving, and so on). For example, the teachings herein maybe applied to any one or combinations of the following technologies orstandards: Code Division Multiple Access (CDMA), Multiple-Carrier CDMA(MCCDMA), Wideband CDMA (W-CDMA), Time Division Multiple Access (TDMA),Frequency Division Multiple Access (FDMA), Single-Carrier FDMA(SC-FDMA), Orthogonal Frequency Division Multiple Access (OFDMA),cdma2000, W-CDMA, TDSCDMA, 802.11 (Wi-Fi), 802.16, Global System forMobile Communication (GSM), Evolved UTRA (E-UTRA), IEEE 802.20,Flash-OFDM®, Long Term Evolution (LTE), Ultra-Mobile Broadband (UMB),Ultra-Wide Band (UWB), Bluetooth®, GSM/General Packet Radio Service(GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio(TETRA), Evolution Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DORev B, High Speed Packet Access (HSPA), High Speed Downlink PacketAccess (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved HighSpeed Packet Access (HSPA+), AMPS, or other technology of 3G, 4G, or 5G.

The techniques may be incorporated into (such as implemented within orperformed by) a variety of wired or wireless apparatuses (such as nodesor devices). In some implementations, a node includes a wireless node.Such a wireless node may provide, for example, connectivity to or for anetwork [such as a wide area network (WAN) such as the Internet or acellular network] via a wired or wireless communications link. In someimplementations, a wireless node may be an access point or a userterminal.

EXAMPLE OF WIRELESS COMMUNICATIONS NETWORK

FIG. 1 illustrates a multiple-access Multiple Input Multiple Output(MIMO) network 100 with access points and user terminals. Forsimplicity, only one access point 110 is shown in FIG. 1. An accesspoint (AP) is generally a fixed station that communicates with the userterminals and also may be referred to as a base station or some otherterminology. A user terminal may be fixed or mobile and also may bereferred to as a mobile station, an access terminal, a station (STA), aclient, user equipment or some other terminology. A user terminal may bea cellular phone, a personal digital assistant (PDA), a handheld device,a wireless modem, a laptop computer, a personal computer, etc.

The access point 110 may communicate with one or more user terminals orstations 120 at any given moment on the downlink and uplink. Thedownlink (i.e., forward link) is the communications link from the accesspoint to the user terminals, and the uplink (i.e., reverse link) is thecommunications link from the user terminals to the access point. A userterminal also may communicate peer-to-peer with another user terminal. Anetwork controller 130 couples to and provides coordination and controlfor the access points.

The MIMO network 100 employs multiple transmit and multiple receiveantennas for data transmission on the downlink and uplink. The accesspoint 110 is equipped with a number N_(ap) of antennas and representsthe multiple-input (MI) for downlink transmissions and themultiple-output (MO) for uplink transmissions. A set N_(u) of selecteduser terminals 120 collectively represents the multiple-output fordownlink transmissions and the multiple-input for uplink transmissions.In some implementations, it may be desirable to have N_(ap)≥N_(u)≥1 ifthe data symbol streams for the N_(u) user terminals are not multiplexedin code, frequency or time by some means. N_(u) may be greater thanN_(ap) if the data symbol streams can be multiplexed using differentcode channels with CDMA, disjoint sets of sub-bands with OFDM, and soon. Each selected user terminal transmits user-specific data to andreceives user-specific data from the access point. In general, eachselected user terminal may be equipped with one or multiple antennas(i.e., N_(ut)≥1). The N_(u) selected user terminals can have the same ordifferent number of antennas.

The MIMO system or network 100 may be a time division duplex (TDD)network or a frequency division duplex (FDD) network. For a TDD network,the downlink and uplink share the same frequency band. For an FDDnetwork, the downlink and uplink use different frequency bands. The MIMOnetwork 100 also may use a single carrier or multiple carriers fortransmission. Each user terminal may be equipped with a single antenna(such as in order to keep costs down) or multiple antennas (such aswhere the additional cost can be supported). The MIMO network 100 mayrepresent a high speed Wireless Local Area Network (WLAN) operating in a60 GHz band.

FIG. 2 illustrates example components of the access point 110 and userterminal or station 120 illustrated in FIG. 1, which may be used toimplement aspects of the present disclosure. One or more components ofthe access point 110 and station 120 may be used to practice aspects ofthe present disclosure. For example, antenna 224, transmitter/receiverunit 222, processors 210, 220, 240, 242, and/or controller 230 orantenna 252, transmitter/receiver 254, processors 260, 270, 288, and290, and/or controller 280 may be used to perform the operationsdescribed herein and illustrated with reference to FIGS. 5, 5A, 7, and7A.

FIG. 2 shows a block diagram of the access point/base station 110 andtwo user terminals 120 m and 120 x in a MIMO network 100. The accesspoint 110 is equipped with N_(ap) antennas 224 a through 224 ap. Theuser terminal 120 m is equipped with N_(ut,m) antennas 252 ma through252 mu, and the user terminal 120 x is equipped with N_(ut,x) antennas252 xa through 252 xu. The access point 110 is a transmitting entity forthe downlink and a receiving entity for the uplink. Each user terminal120 is a transmitting entity for the uplink and a receiving entity forthe downlink. As used herein, a “transmitting entity” is anindependently operated apparatus or device capable of transmitting datavia a frequency channel, and a “receiving entity” is an independentlyoperated apparatus or device capable of receiving data via a frequencychannel. In the following description, the subscript “dn” denotes thedownlink, the subscript “up” denotes the uplink, N_(up) user terminalsare selected for simultaneous transmission on the uplink, and N_(dn)user terminals are selected for simultaneous transmission on thedownlink. Moreover, N_(up) may or may not be equal to N_(dn), andN_(up), and N_(dn) may include static values or can change for eachscheduling interval. Beamforming (such as beam-steering) or some otherspatial processing techniques may be used at the access point and userterminal.

On the uplink, at each user terminal 120 selected for uplinktransmission, a TX data processor 288 receive traffic data from a datasource 286 and control data from a controller 280. The controller 280may be coupled with a memory 282. The TX data processor 288 processes(such as encodes, interleaves, and modulates) the traffic data{d_(up,m)} for the user terminal based on the coding and modulationschemes associated with the rate selected for the user terminal andprovides a data symbol stream {s_(up,m)}. A TX spatial processor 290performs spatial processing on the data symbol stream {s_(up,m)} andprovides N_(ut,m) transmit symbol streams for the N_(ut,m) antennas.Each transmitter unit (TMTR) 254 receives and processes (such asconverts to analog, amplifies, filters, and frequency upconverts) arespective transmit symbol stream to generate an uplink signal. TheN_(ut,m) transmitter units 254 provide N_(ut,m) uplink signals fortransmission from the N_(ut,m) antennas 252 to the access point 110.

A number N_(up) of user terminals may be scheduled for simultaneoustransmission on the uplink. Each of these user terminals performsspatial processing on its data symbol stream and transmits its set oftransmit symbol streams on the uplink to the access point.

At the access point 110, the N_(ap) antennas 224 a through 224 apreceive the uplink signals from all N_(up) user terminals transmittingon the uplink. Each antenna 224 provides a received signal to arespective receiver unit (RCVR) 222. Each receiver unit 222 performsprocessing complementary to that performed by the transmitter unit 254and provides a received symbol stream. An RX spatial processor 240performs receiver spatial processing on the N_(ap) received symbolstreams from the N_(ap) receiver units 222 and provides N_(up) recovereduplink data symbol streams. The receiver spatial processing is performedin accordance with the channel correlation matrix inversion (CCMI),minimum mean square error (MMSE), successive interference cancellation(SIC), or some other technique. Each recovered uplink data symbol stream{s_(up,m)} is an estimate of a data symbol stream {s_(up,m)} transmittedby a respective user terminal. An RX data processor 242 processes (suchas demodulates, de-interleaves, and decodes) each recovered uplink datasymbol stream {s_(up,m)} in accordance with the rate used for thatstream to obtain decoded data. The decoded data for each user terminalmay be provided to a data sink 244 for storage and a controller 230 forfurther processing.

On the downlink, at the access point 110, a TX data processor 210receives traffic data from a data source 208 for N_(dn) user terminalsscheduled for downlink transmission, control data from a controller 230,and possibly other data from a scheduler 234. The various types of datamay be sent on different transport channels. The TX data processor 210processes (such as encodes, interleaves, and modulates) the traffic datafor each user terminal based on the rate selected for that userterminal. The TX data processor 210 provides N_(dn) downlink data symbolstreams for the N_(dn) user terminals. A TX spatial processor 220performs spatial processing on the N_(dn) downlink data symbol streams,and provides N_(ap) transmit symbol streams for the N_(ap) antennas.Each transmitter unit (TMTR) 222 receives and processes a respectivetransmit symbol stream to generate a downlink signal. The N_(ap)transmitter units 222 provide N_(ap) downlink signals for transmissionfrom the N_(ap) antennas 224 to the user terminals. The decoded data foreach STA may be provided to a data sink 272 for storage and/or acontroller 280 for further processing.

At each user terminal 120, the N_(ut,m) antennas 252 receive the N_(ap)downlink signals from the access point 110. Each receiver unit (RCVR)254 processes a received signal from an associated antenna 252 andprovides a received symbol stream. An RX spatial processor 260 performsreceiver spatial processing on N_(ut,m) received symbol streams from theN_(ut,m) receiver units 254 and provides a recovered downlink datasymbol stream {S_(dn,m)} for the user terminal. The receiver spatialprocessing can be performed in accordance with the CCMI, MMSE, or otherknown techniques. An RX data processor 270 processes (such asdemodulates, de-interleaves, and decodes) the recovered downlink datasymbol stream to obtain decoded data for the user terminal.

At each user terminal 120, the N_(ut,m) antennas 252 receive the N_(ap)downlink signals from the access point 110. Each receiver unit (RCVR)254 processes a received signal from an associated antenna 252 andprovides a received symbol stream. An RX spatial processor 260 performsreceiver spatial processing on N_(ut,m) received symbol streams from theN_(ut,m) receiver units 254 and provides a recovered downlink datasymbol stream {s_(dn,m)} for the user terminal. The receiver spatialprocessing is performed in accordance with the CCMI, MMSE, or some othertechnique. An RX data processor 270 processes (such as demodulates,de-interleaves, and decodes) the recovered downlink data symbol streamto obtain decoded data for the user terminal.

FIG. 3 illustrates various components that may be used in a wirelessdevice 302 that may be employed within the MIMO network 100. Thewireless device 302 is an example of a device that may be configured toimplement the various methods described herein. The wireless device 302may be an access point 110 or a user terminal 120.

The wireless device 302 may include a processor 304 which controlsoperation of the wireless device 302. The processor 304 also may bereferred to as a central processing unit (CPU). Memory 306, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 304. A portion of thememory 306 also may include non-volatile random access memory (NVRAM).The processor 304 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 306. Theinstructions in the memory 306 may be executable to implement themethods described herein.

The wireless device 302 also may include a housing 308 that may includea transmitter 310 and a receiver 312 to allow transmission and receptionof data between the wireless device 302 and a remote location. Thetransmitter 310 and the receiver 312 may be combined into a transceiver314. A plurality of transmit antennas 316 may be attached to the housing308 and electrically coupled to the transceiver 314. The wireless device302 also may include (not shown) multiple transmitters, multiplereceivers, and multiple transceivers.

The wireless device 302 also may include a signal detector 318 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 314. The signal detector 318 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 302 also mayinclude a digital signal processor (DSP) 320 for use in processingsignals.

The various components of the wireless device 302 may be coupledtogether by a bus system 322, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus.

A contention-based protocols is a communications protocol for operatingwireless telecommunication equipment that allows many devices to use thesame radio channel without pre-coordination. Each device contends for atime period to communicate its information such as data and controlinformation. Once the device won the contention for a particular timeperiod, which is also known as a transmission opportunity (hereinafter“TXOP”), such device could transmit information and also could grantpermission to another device to transmit during such TXOP.

During a particular TXOP, an owner of such TXOP could also perform linkadaptation so as to determine a modulation scheme and a coding rate ofthe error correction that are ideal for communication according to thequality of the radio link. If the conditions of the radio link are good,a high-level efficient modulation scheme and a small amount of errorcorrection is used. For example, a modulation and coding scheme (MCS)with an index value 5 is used when the conditions of the radio link aregood and a MCS with an index value of 2 is used when the conditions ofthe radio link are not as good. In general, a higher MCS means moreinformation can be transmitted but the chance of reception of thetransmitted information by another device is less than a chance ofreception of the transmitted information associated with a lower MCS.

To maximize data throughput, the owner of the TXOP (hereinafter the“initiator”) can also grant permission to another device (responder) totransmit information during the TXOP. That is, reverse direction isenabled and thus both initiator and responder could simultaneouslyperform link adaptation. If so, the ACKs or Block ACKs being transmittedby the responder to the initiator might not be detected by the initiatorand vice versa. Thus, it would be better if the responder would transmitdata when link adaptation is not being performed by the initiator sincedata transmission by the responder would skew channel conditions and,thus, yield a lower MCS determined by the initiator via link adaptation.

The following examples of apparatuses, methods, computer readablemediums and wireless nodes effectively (1) perform link adaptationduring the TXOP and, thereafter, allow a responder to transmit dataduring the remainder of the TXOP and (2) determine whether linkadaptation is being performed during a TXOP owned by the initiator and,if not, transmit data during the TXOP.

EXAMPLE OF EXPLICIT INDICATION THAT INITIATOR IS FINISHED PERFORMINGLINK DAPTATION

FIG. 4 illustrates messages being exchanged between an initiator and aresponder during a transmission opportunity owned by the initiator andwith a reverse direction bit initially set to 0 in accordance withcertain aspects of the present disclosure. The initiator can be an APsuch as the AP 110 of FIG. 1 or FIG. 2 and the responder can be an STAsuch as one of the stations of FIG. 1 or STA 120 m of FIG. 2. In otheraspects, the initiator can be an STA and the responder can be the AP orboth initiator and responder are STAs.

In general, FIG. 4 illustrates the initiator performing link adaptationduring the TXOP owned by the initiator. To proceed with link adaptation,the initiator sets a reverse direction bit (hereinafter “RD bit”) to afirst value to indicate only the initiator can transmit data during theTXOP. Once the initiator is finished with link adaptation, it sets a RDbit to a second value to indicate the responder can also transmit dataduring the remainder of the TXOP.

More specifically, the initiator initially sets a RD bit to a firstvalue such as 0 to indicate that the responder can only transmit controlinformation during the TXOP or cannot transmit any data during the TXOP.The initiator then begins link adaptation by transmitting the RD bit anddata to the responder via message 400. The initiator applies a MCS(x) tothe data with “x” being the index value and then transmits the modulatedand coded data to the responder. The responder then transmits anacknowledgement (hereinafter “ACK”) 402 such as an ACK frame indicatingit had received the transmitted data. In certain aspects, the message400 includes multiple data frames therein and thus the responder couldsend a block ACK frame having a bit map with a particular bit indicatinga particular data frame was received.

Based on the ACK 402, the initiator determines a frame error rate(hereinafter “FER”) and thereafter compares the FER to a target errorrate, which is preferably 10% and could be adjusted upward to, e.g., 15%or downward to, e.g., 5%. If the comparison indicates the FER is lessthan or equal to the target error rate per block 404, the initiatorcould certainly continue to use MCS(x) for data transmission but theinitiator would be able to send more data if it could use a higher MCS.Thus, the initiator applies a higher MCS to additional data andtransmits such modulated and coded additional data 408 to the responder.In the aspect depicted in FIG. 4, the higher MCS is MCS(x+1).Alternatively, the initiator can select a MCS having an index value thatis 2 or more than the value of x and, for the selection, the initiatoris aware that selecting a higher MCS for modulating and coding datatends to lead to a lesser chance of reception of such modulated andcoded data by responder.

After the data transmission 408, the initiator receives ACK 410 from theresponder, determines another FER based on ACK 410 and compares the FERto the target error rate. Block 412 indicates the FER is still less thanor equal to the target error rate and thus the initiator applies an evenhigher MCS such as MCS(x+2) as depicted in FIG. 4 to more data andtransmits such modulated and coded data 414 to the responder.Thereafter, initiator receives ACK 416 from the responder, determinesanother FER based on ACK 416 and compares the FER to the target errorrate. Block 418 indicates the latest FER is greater than the targeterror rate and such indication means the initiator is finished with linkadaptation since the previous MCS or MCS(x+1) is the highest MCS thatcould be used with tolerable error rate associated with data receptionat an intended receiver such as the responder. As a result, theinitiator sets a RD bit to 1 and transmits such RD bit 420 to theresponder so as to allow the responder to transmit any informationincluding data during the remainder of the TXOP. In certain aspects, theresponder can begin its own link adaptation during the TXOP bytransmitting data to another device such as the initiator sinceconditions of the radio link at the initiator for data reception willlikely be different from the conditions of the radio link at theresponder for data reception.

Certain messages of with FIG. 4 are further explained below inaccordance with certain aspects being described herein with respect toFIG. 5.

FIG. 5 is a flow diagram of example operations 500 for wirelesscommunications, in accordance with certain aspects of the presentdisclosure. The operations 500 may be performed by an apparatus or awireless device 302 of FIG. 3.

At block 502, the apparatus, which could also be the initiator of FIG.4, obtains a TXOP by contending for it. Since the apparatus is the ownerof the TXOP, it can transmit whatever it wants.

At block 504, the apparatus generates a plurality of first frames fortransmission to a second apparatus, which could be the responder of FIG.4. The plurality of first frames has at least one frame with a controlfield therein and at least one frame with data therein, i.e., at leastone data frame. In certain aspects, the frame having the control fieldis a control frame such as a NULL frame or QoS NULL frame having no datapayload therein and the control field has a RD bit with a first valuesuch as 0 to indicate that the second apparatus can only transmitcontrol information during the TXOP. Control information can be an ACKframe or a block ACK frame. However, the second apparatus cannottransmit any data after reception of the RD bit with the value of 0since the apparatus is performing link adaptation during this TXOP.

At block 506, the apparatus applies a first MCS to the first frames. Incertain aspects, the first MCS can be a MCS that was previously used bythe apparatus to communicate with the second apparatus. At block 508,the apparatus outputs the modulated and coded first frames such asmessage 400 for transmission to the second apparatus during the TXOP. Atblock 510, the apparatus obtains an acknowledgment such as ACK 402 fromthe second apparatus indicating at least one data frame was received bythe second apparatus. In certain aspects, the ACK is an ACK frame or ablock ACK frame, which indicates two or more data frames were receivedby the second apparatus.

Based on the ACK, the apparatus determines a first error rate such as aframe error rate at block 512, compares the error rate to a target errorrate at block 514 and takes one or more actions based on the comparisonat block 516.

If the comparison at block 514 indicates the first error rate is lessthan or equal to the target error rate and an index value of the firstMCS is the highest among index values of MCSs associated with theapparatus including the first MCS, the one or more actions at block 516include (a) generating a second frame having a control field with asecond value indicating the second apparatus can, after reception of thesecond frame, transmit data, (b) applying the first MCS to the secondframe and (c) output the modulated and coded second frame fortransmission to the second apparatus during the TXOP.

For this aspect, the first MCS is the highest MCS that can be used bythe apparatus to modulate and code data. Since the first or the highestMCS yields tolerable FER, the apparatus is finished with link adaptationand, thereafter, sets the second value of the control field of thesecond frame to a value different from the first value of 0. Thus, thesecond value is preferably 1 to indicate that the second apparatus isallowed to transmit data as well as control information during theremainder of the TXOP. By allowing the second device to also transmitany information during the remainder of the TXOP, efficient use of suchTXOP for communication is achieved. For example, if the second apparatushas data in its buffer for the apparatus, the second apparatus cantransmit such data to the apparatus during the apparatus's TXOP withoutcontending for a TXOP or waiting for its own TXOP. In addition, thesecond apparatus can also begin its own link adaptation during theremainder of the TXOP.

After outputting the modulated and coded second frame for transmissionat block 516, the apparatus can obtain another ACK, a data frame or bothfrom the second apparatus. In certain aspects, the second frame is acontrol frame such as a NULL frame or QoS NULL frame. In other aspects,the second frame also includes data payload therein.

If the comparison at block 514 indicates the first error rate is lessthan or equal to the target error rate, the one or more actions at block516 include (1) generating at least one second frame having data, (2)applying a second MCS to the at least one second frame, wherein an indexvalue of the second MCS is higher than an index value of the first MCSand (3) outputting the at least one modulated and coded second frame fortransmission to the second apparatus during the TXOP.

For this aspect, the apparatus realizes that using the first MCS mightnot be optimal or yield the greatest data throughput especially if thefirst error rate is less than the target error rate. Thus, the apparatusthen uses a MCS that is higher than the first MCS to modulate and codeadditional data for transmission to the second apparatus similar to thedata transmission 408 or 414 of FIG. 4 and, if the FER continues to beless or equal to the target error rate, repeats steps (1)-(3) of block516 by generating another frame having data (data frame) and applying ahigher MCS until the FER associated with a particular MCS is greaterthan the target error rate. At that time, the apparatus realizes the MCSused immediately prior to the latest MCS should be used forcommunication until the next link adaptation. As a result, the currentlink adaptation is finished, and the apparatus sets a RD bit to a valueof 1 and outputs such RD bit for transmission to the second apparatus.

If the comparison at block 514 indicates the first error rate is greaterthan the target error, the one or more actions at block 516 include (i)generating at least one second frame having data, (ii) applying a secondMCS to the at least one second frame, wherein an index value of thesecond MCS is lower than an index value of the first MCS and (iii)outputting the at least one modulated and coded second frame fortransmission to the second apparatus during the TXOP.

For this aspect, the apparatus realizes data reception at the secondapparatus was not robust since the FER associated with the first MCS isgreater than the target error rate. Thus, the apparatus then uses alower MCS, i.e., the second MCS with the index value being lower thanthe index value of the first MCS to encode and modulate data for furthertransmission. In certain aspects, the second MCS is a MCS that waspreviously used by the apparatus to communicate with the secondapparatus during the same TXOP or a previous TXOP. In other aspects, thesecond MCS is one lower than the first MCS. That is, if the first MCShas an index value of 6, the second MCS has an index value of 5.

If the FER continues to be greater than the target error rate, theapparatus repeats steps (i)-(iii) by generating another data frame andusing a MCS with an index value one less than the index value of the MCSassociated with the FER that is greater than the target error rate. Oncethe FER is less than or equal to the target error rate, the current linkadaptation is finished. Thus, the apparatus sets a RD bit to a value of1 and outputs such RD bit for transmission to the second apparatus.

EXAMPLE OF IMPLICIT INDICATION THAT INITIATOR IS NOT PERFORMING LINKDAPTATION

FIG. 6 illustrates messages being exchanged between an initiator and aresponder during a transmission opportunity owned by the initiator andwith a reverse direction bit initially set to 1 in accordance withcertain aspects of the present disclosure. The initiator can be an APsuch as the AP 110 of FIG. 1 or FIG. 2 and the responder can be an STAsuch as one of the stations of FIG. 1 or STA 120 m of FIG. 2. In otheraspects, the initiator can be an STA and the responder can be the AP orboth initiator and responder are STAs.

In general, FIG. 6 illustrates the initiator optionally setting the RDbit to a first value to indicate the responder can transmit anyinformation during the TXOP owned by the initiator. Regardless, theresponder does not transmit any data during such TXOP until theresponder determines that link adaptation is not being performed by theinitiator. For example, such determination can be a result of theresponder recognizing the MCS being used by the initiator to transmitdata has not changed for several data transmissions.

As discussed above, the responder may receive a message 600 having a RDbit with value of 1 therein to indicate the responder can transmit anyinformation, e.g., control information and data, during the TXOP.Regardless, the responder refrains from transmitting any data.Thereafter, the responder receives a message 602 with frame 1 therein.

At block 603, the responder determines that MCS(x) was used to modulateand code such frame 1, stores the result of the determination or MCS(x)in its memory and transmits an acknowledgement 604 to the initiatorindicating frame 1 was received. Thereafter, the responder furtherreceives a message 606 with frame 2 therein.

At block 607, the responder determines that MCS(y) was used to modulateand code such frame 2, increases a value of a counter(0) by 1 from theinitial value of 0 since MCS(y)=MCS(x) and compares counter(1) to atarget value of 2 as depicted by Tg(2) in FIG. 6. If MCS(y) does notequal MCS(x), the responder does not increase the counter value and willuse MCS(y) as the baseline MCS for the next comparison.

Regarding the counter value, the responder sets the initial value of thecounter to 0 at the start of each TXOP and increases such counter valueby 1 if a previous MCS used to transmit data by the initiator is thesame as the latest or current MCS used to transmit data by the initiatoror maintains such counter value at 0 if the previous MCS is differentfrom the current MCS. If a MCS associated with the next datatransmission also matches the previous MCS, the responder continues toincrease the counter value by 1. If not, the responder resets thecounter value to 0 and will use the latest MCS for comparison with a MCSassociated with the next data transmission from the initiator and so on.

Regarding the target value, such value is a target of when the respondercan transmit data if the counter value is the same as the target value.In other words, when the counter value is equal to the target value,that equivalence indicates the initiator is not performing linkadaptation and thus the responder can transmit data. In addition, theresponder can determine the target value for its own use or can receivethe target value from the responder.

In certain aspects, the responder can determine the target value basedon communication with the initiator during a previous or different TXOP.For Wi-Fi communications, the conditions of the radio link typically donot change drastically and thus if the initiator was performing linkadaptation during the previous TXOP, it would be unlikely that theinitiator will perform link adaptation again in the following TXOP.Therefore, the responder preferably sets target value to a low valuesuch as 1 or 2. Alternatively, the responder can set the target value to3 or higher if the responder determines that the initiator has notperformed any link adaptation for a threshold period of time such asthree consecutive TXOPs.

In other aspects, the initiator informs the responder what target valueto use. For example, if the initiator plans on transmitting threetraining frames by using the same MCS to see whether the initiatorshould use such MCS, the initiator can inform the responder in advanceof its plan and thus the responder would then set the target value to 2since the MCS associated with the first training frame would not becompared to any MCS and it would be used as a baseline MCS such asMCS(x) of FIG. 6.

Since counter(1) is still less than Tg(2) per comparison at block 607,the responder transmits an acknowledgement 608 indicating frame 2 wasreceived. Thereafter, the responder receives a message 610 with frame 3therein.

At block 611, the responder determines that MCS(z) was used to modulateand code such frame 2, increases counter(1) by 1 since MCS(z)=MCS(y) andcompares counter(2) with Tg(2). The comparison shows that the countervalue of 2 and target value of 2 are equal and thus their equalityimplicitly indicates that the initiator is not performing linkadaptation or is finished with performing link adaptation since the MCSbeing used by the initiator has remained constant. Alternatively, theresponder can be configured to transmit data if the counter value isgreater than the target value, which indicates no link adaptation isbeing performed by the initiator.

Based on the counter value being equal to or greater than the targetvalue, the responder can transmit data or data frame(s) 612 to theinitiator during the TXOP. In certain aspects, the responder can beginlink adaptation starting with the transmission of data frame 612.

Certain messages of with FIG. 4 are further explained below inaccordance with certain aspects being described herein with respect toFIG. 7.

FIG. 7 is a flow diagram of example operations 700 for wirelesscommunications, in accordance with certain aspects of the presentdisclosure. The operations 700 may be performed by an apparatus or awireless device 302 of FIG. 3.

At block 702, the apparatus, which could be the responder of FIG. 6,obtains at least one first frame such as a frame in the message 602, 606or 610 of FIG. 6 from a second apparatus, which could be the initiatorof FIG. 6, during a TXOP owned by the second apparatus. In certainaspects, the at least one first frame includes a control field having aRD bit with a first value such as 1 indicating the apparatus cantransmit data during the TXOP. Even though the second apparatus allowsthe apparatus to transmit data, the apparatus won't transmit any datauntil it determines that the second apparatus is not performing linkadaption or is finished with performing link adaptation. Thus, thereception or non-reception of the RD bit with the value of 1 does notchange the operations of the apparatus.

At block 704, the apparatus determines a MCS associated with the atleast one first frame. Such determination is similar to thedetermination associated with one of the blocks 603, 607 and 611 of FIG.6.

At block 706, the apparatus increases a value of a counter if thedetermined MCS, e.g., MCS(y) of FIG. 6, is the same as a MCS associatedwith a frame previously obtained by the apparatus during the same TXOP,e.g., MCS(x) of FIG. 6. See, also, block 607 of FIG. 6.

At block 708, the apparatus takes one or more actions based on thecounter value.

If the counter value is equal to or greater than a target value, the oneor more actions include generating at least one second frame having dataand outputting the at least one second frame for transmission to thesecond apparatus during the TXOP. In other aspects, before outputtingthe at least one second data frame for transmission, the one or moreactions include generating an acknowledgement indicating data of theleast one first frame was received by the apparatus and outputting theACK for transmission to the second apparatus during the TXOP.

Before outputting the at least one second data frame and the ACK fortransmission, the apparatus can use the same MCS to modulate and codethe at least one second data frame and the ACK. Alternatively, the MCSassociated with the at least one second data frame is higher than theMCS associated with the ACK. This is especially true if the transmissionof the at least one second data frame is the start of link adaptation bythe apparatus, which is trying to find the highest MCS that it can usewithout compromising data reception. Furthermore, the apparatus can usethe same MCS associated with a previous data transmission to modulateand code the at least one second data frame especially if the apparatushad received an ACK indicating such previous data transmission wassuccessful. Moreover, the apparatus can use a MCS, which is higher thanthe MCS associated with the previous successful data transmission, tomodulate and code the at least one second data frame especially, again,if the transmission of the at least one second data frame is the startof link adaptation.

If the counter value is less than the target value, the one or moreactions include (1) generating an acknowledgement indicating data of theleast one first frame was received by the apparatus, (2) outputting theACK for transmission to the second apparatus during the TXOP, (3)obtaining at least one second frame from the second apparatus during theTXOP, (4) determining a MCS associated with the at least one secondframe and (5) increasing the counter value if the MCS associated withthe at least one second frame is the same as the MCS associated with theleast one first frame. If the counter value is still less than thetarget value, repeat steps (1)-(5) by generating another ACK andobtaining another frame from the second apparatus.

In certain aspects, the at least one first frame obtained per block 702includes a control field having a first value indicating the apparatuscan transmit data during the TXOP and, thus, the one or more actionsinclude generating a second frame comprising data if the counter valueis equal to or greater than a target value and outputting the secondframe for transmission during the TXOP. As discussed above, even if theapparatus is allowed to transmit data by the TXOP owner during the TXOP,the apparatus does not or refrain from outputting any data fortransmission during such TXOP unless the counter value is equal to orgreater than the target value. That is, the apparatus must determinethat link adaptation is either finished or not being performed duringthe TXOP before the apparatus transmits any data.

The methods disclosed herein include one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c). Asused herein, including in the claims, the term “and/or,” when used in alist of two or more items, means that any one of the listed items can beemployed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” For example, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form. Unlessspecifically stated otherwise, the term “some” refers to one or more.Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase, for example, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, forexample the phrase “X employs A or B” is satisfied by any of thefollowing instances: X employs A; X employs B; or X employs both A andB. All structural and functional equivalents to the elements of thevarious aspects described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 U.S.C. § 112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or,in the case of a method claim, the element is recited using the phrase“step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering. More specifically, operations 500 illustrated in FIG.5 correspond to means 500A illustrated in FIG. 5A and operations 700illustrated in FIG. 7 correspond to means 700A illustrated in FIG. 7A.

For example, means for transmitting (or means for outputting fortransmission) may include a transmitter (e.g., the transmitter unit 222)and/or an antenna(s) 224 of the access point 110 or the transmitter unit254 and/or antenna(s) 252 of the station 120 illustrated in FIG. 2.Means for receiving (or means for obtaining) may include a receiver(e.g., the receiver unit 222) and/or an antenna(s) 224 of the accesspoint 110 or the receiver unit 254 and/or antenna(s) 252 of the station120 illustrated in FIG. 2. Means for processing, means for determining,means for obtaining, means for generating, means for applying, means forcomparing, means for increasing or means for taking one or more actionsmay include a processing system, which may include one or moreprocessors, such as the RX data processor 242, the TX data processor210, the TX spatial processor 220, and/or the controller 230 of theaccess point 110 or the RX data processor 270, the TX data processor288, the TX spatial processor 290, and/or the controller 280 of thestation 120 illustrated in FIG. 2.

In some cases, rather than actually transmitting a frame, a device mayhave an interface to output a frame for transmission (a means foroutputting). For example, a processor may output a frame, via a businterface, to a radio frequency (RF) front end for transmission.Similarly, rather than actually receiving a frame, a device may have aninterface to obtain a frame received from another device (a means forobtaining). For example, a processor may obtain (or receive) a frame,via a bus interface, from an RF front end for reception. In some cases,the interface to output a frame for transmission and the interface toobtain a frame (which may be referred to as first and second interfacesherein) may be the same interface.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration mayinclude a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userterminal 120 (see FIG. 1), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall network or system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunications media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, phasechange memory, ROM (Read Only Memory), PROM (Programmable Read-OnlyMemory), EPROM (Erasable Programmable Read-Only Memory), EEPROM(Electrically Erasable Programmable Read-Only Memory), registers,magnetic disks, optical disks, hard drives, or any other suitablestorage medium, or any combination thereof. The machine-readable mediamay be embodied in a computer-program product.

A software module may include a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may include a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media mayinclude non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may includetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may include a computer program product forperforming the operations presented herein. For example, such a computerprogram product may include a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For example, instructions for performing the operationsdescribed herein and illustrated in the appended figures.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be used.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is:
 1. An apparatus for wireless communicationcomprising: an interface configured to obtain, during a TXOP owned by asecond apparatus, at least one first frame from the second apparatus;and a processing system configured to: determine a MCS associated withthe at least one first frame; increase a value of a counter if the MCSassociated with the at least one first frame is the same as a MCSassociated with a frame previously obtained by the apparatus during theTXOP; and take one or more actions based on the counter value.
 2. Theapparatus of claim 1, wherein: if the counter value is equal to orgreater or greater than a target value, the one or more actions comprisegenerating at least one second frame comprising data; and the interfaceis configured to output the at least one second frame for transmissionto the second apparatus during the TXOP.
 3. The apparatus of claim 2,wherein: the one or more actions further comprise generating anacknowledgement (ACK) indicating data of the least one first frame wasreceived by the apparatus; and the interface is further configured tooutput the ACK for transmission to the second apparatus during the TXOP.4. The apparatus of claim 3, wherein a MCS associated with the at leastone second frame is the same as a MCS associated with the ACK.
 5. Theapparatus of claim 3, wherein an index value of the MCS associated withthe at least one second frame is higher than an index value of the MCSassociated with the ACK.
 6. The apparatus of claim 3, wherein a MCSassociated with the at least one second frame is the same as a MCSassociated with a frame comprising data that was previously outputted bythe apparatus for transmission.
 7. The apparatus of claim 3, wherein anindex value of a MCS associated with the at least one second framehigher than an index value of a MCS associated with a frame comprisingdata that was previously outputted by the apparatus for transmission. 8.The apparatus of claim 1, wherein: if the counter value is less than atarget value, the one or more actions comprise generating anacknowledgement (ACK) indicating data of the least one first frame wasreceived by the apparatus; the interface is further configured to:output the ACK for transmission to the second apparatus during the TXOP;and obtain at least one second frame from the second apparatus duringthe TXOP; and the processing system is further configured to: determinea MCS associated with the at least one second frame; and increase thecounter value if the MCS associated with the at least one second frameis the same as the MCS associated with the least one first frame.
 9. Theapparatus of claim 2, wherein the interface is further configured toobtain the target value from the second apparatus.
 10. The apparatus ofclaim 2, wherein the processing system is further configured todetermine the target value based on communication with the secondapparatus during at least one previous TXOP.
 11. The apparatus of claim1, wherein: the at least one first frame comprises a control fieldhaving a first value indicating the apparatus can transmit data duringthe TXOP; the one or more actions comprise generating a second framecomprising data if the counter value is equal to or greater than atarget value; and the interface is further configured to output thesecond frame for transmission to the second apparatus during the TXOP.12. The apparatus of claim 11, wherein the first value is
 1. 13. Amethod for wireless communication by an apparatus, comprising:obtaining, during a TXOP owned by a second apparatus, at least one firstframe from the second apparatus; determining a MCS associated with theat least one first frame; increasing a value of a counter if the MCSassociated with the at least one first frame is the same as a MCSassociated with a frame previously obtained by the apparatus during theTXOP; and taking one or more actions based on the counter value.
 14. Themethod of claim 13, wherein: if the counter value is equal to or greaterthan a target value, said taking one or more actions comprisesgenerating at least one second frame comprising data; and the methodfurther comprising outputting the at least one second frame fortransmission to the second apparatus during the TXOP.
 15. The method ofclaim 14, wherein: said taking one or more actions further comprisesgenerating an acknowledgment (ACK) indicating data of the least onefirst frame was received by the apparatus; and the output furthercomprises outputting the ACK for transmission to the second apparatusduring the TXOP.
 16. The method of claim 13, wherein: if the countervalue is less than a target value, said taking one or more actionscomprises generating an acknowledgment (ACK) indicating data of theleast one first frame was received by the apparatus; the method furthercomprising outputting the ACK for transmission to the second apparatusduring the TXOP; and said obtaining further comprises obtaining at leastone second frame from the second apparatus during the TXOP; thedetermination further comprises determining a MCS associated with the atleast one second frame; and the increase further comprises increasingthe counter value if the MCS associated with the at least one secondframe is the same as the MCS associated with the least one first frame.17. The method of claim 14, wherein said obtaining further comprisesobtaining the target value from the second apparatus.
 18. The method ofclaim 14, wherein the determination further comprises determining thetarget value based on communication with the second apparatus during atleast one previous TXOP.
 19. The method of claim 13, wherein: the atleast one first frame comprises a control field having a first valueindicating the apparatus can transmit data during the TXOP; said takingone or more actions comprises generating a second frame comprising dataif the counter value is equal to or greater than a target value; and themethod further comprising outputting the second frame for transmissionto the second apparatus during the TXOP.
 20. A wireless node comprising:a receiver configured to receive, during a TXOP owned by a secondapparatus, at least one first frame from the second apparatus; and aprocessing system configured to: determine a MCS associated with the atleast one first frame; increase a value of a counter if the MCSassociated with the at least one first frame is the same as a MCSassociated with a frame previously obtained by the apparatus during theTXOP; and take one or more actions based on the counter value.